DE3117000C2 - Phototropic glass with a refractive index? 1.59, an Abbe number? 40 and a density ≦ 3.2 g / cm? 3? - Google Patents

Abstract

A phototropic glass with the optical position n ↓ d 1.59 and v ↓ d 40 and with a density of 3.2 g.cm ↑ - ↑ 3 is described for the first time. Its composition lies in the system SiO ↓ 2 - R ↓ 2O ↓ 3 - R ↓ 2O - RO - RO ↓ x - R ↓ 2O ↓ 5, where R ↓ 2O ↓ 3 for Al ↓ 2O ↓ 3, B ↓ 2O ↓ 3 and Rare earth oxides, R ↓ 2O for alkali metal oxides, RO for alkaline earth metal oxides, ZnO, SnO, PbO, RO ↓ x for GeO ↓ 2, ZrO ↓ 2, TiO ↓ 2, WO ↓ 3, and R ↓ 2O ↓ 5 for Nb ↓ 2O ↓ 5 , Ta ↓ 2O ↓ 5, P ↓ 2O ↓ 5 stand.

Description

Ag ₂ O at least 0.1 bromine at least 0.1 chlorine at least 0.1 and Copper oxide at least 0.004

2. Glass according to claim 1, characterized in that the La ₂ O _{3 is} completely or partially replaced by other SeI-ten earth oxides.

3. Glass according to one of claims 1 or 2, characterized in that it is for the purpose of a Brown color in the exposed state is doped with precious metals.

4. Glass according to one of claims 1 to 3, characterized in that it also contains up to 1 wt .-% Contains coloring oxides.

The aim of the invention is a silver halide-containing phototropic borosilicate glass that can be used as a spectacle lens can be found, and this is due to its particular suitability for diopters with plus lenses over + 4 D to + 25 D or in the case of minus lenses above —4 D to —25 D. The aim of the invention is therefore a phototropic, light, high-refraction spectacle lens with low dispersion.

Photochromic glasses are mainly used today as spectacle lenses and are also being used more and more as corrective lenses for ametropia. For The correction of ametropia with glass, which has a refractive index of 1,523, will be at higher Always have diopters (larger visual defects) on the glasses

ίο more voluminous; that means greater weight of the glasses. That is why high-refractive and, at the same time, relatively light spectacle lenses have been searched for and found, but they have So far the attempt to produce such lenses with photochromic properties has failed. the reason for this is the composition of high-refractive, lightweight eyeglass lenses that do not allow the precipitation of silver halide-containing substances necessary for phototropy Areas in the glass can be achieved through appropriate handling conditions. For photochromic This is the case with glasses based on silver halides Phase separation essential.

If you melt z. B. the well-known high-index, lightweight glasses of DE-PS 22 59 183 with carriers the phototropy, the result is a white opaque mass that cannot be used as a spectacle lens. The state of the art in the field of high-index, lightweight glasses is well represented by DE-PS 22 59 183, in the field of photochromic Glasses by DE-PS 24 04 752 and DE-PS 22 23 629.

The glasses according to DE-PS 22 23 629 belong to the same basic glass system as the glasses according to the invention and largely overlap in their areas of composition and optical data. Due to their significantly lower SiO ₂ content, these glasses do not achieve the objective of the invention, a phototropic, high-refraction spectacle lens with low dispersion and at the same time a low density (<g / cm ³ ).

When checking the conventional silver halide-containing, photochromic glasses, insofar as they have properties deviating from the standard refractive index for spectacle lenses from na - 1.523, it was found that it seems impossible to use a SiO ₂ -containing phototropic glass with a refractive index greater than or equal to 1.59, a Abbe number greater than or equal to 40 and a density less than or equal to 3.2 g / cm ³ . DE-OS 21 40 915 contains glasses with a relatively high refractive index, but the glasses should not _{contain SiO 2} , because otherwise the product becomes opaque.

If this result is transferred to the glasses of DE-PS 22 59 183, one recognizes the great difficulty of producing higher refractive index, lightweight SiO ₂ glasses with photochromic properties: both higher refractive index lightweight glasses, provided with the components silver and halogens, such as Photochromic glasses with a higher refractive index, provided with SiO ₂ for stabilization and suitable for mass production, also become cloudy to opaque.

The glasses of DE-OS 21 40 915 also have density values above 3.2 g / cm ³ . The examination of the glasses according to DE-OS 22 56 775 only produced glasses with refractive indices less than 1.59, that of the glasses according to DE-OS 22 60 879 only glasses with densities above 3.2 g / cm ³ .

All known phototropic glasses mentioned do not allow the combination of the criteria phototropy, low density, low dispersion and high refractive index.

31 yl 000

The Abbezahl

V -

"F-" C

is important insofar as it is disruptive at values <40 Color fringes when viewed from an angle due to excessive dispersion, d. H. too strong wavelength dependence of the refractive index. Such color fringes must be avoided.

The feasibility under the conditions customary today is also important. Certain raw materials, such as B. tantalum oxide, have such high prices today that their use for spectacle lenses is only possible to a very limited extent, although they are due to their effect on network formation, d. H. of the highest interest for the devitrification stability, which is so important in the production process are.

In addition, for reasons of mass production using a tub and automatic press (viscosity and crystallization _{criteria), an SiO 2} content of at least 10% by weight is essential for such a spectacle lens.

The aim of the invention is glasses of the type mentioned at the beginning which have a refractive index n </ equal to or greater than 1.59, an Abbe number equal to or greater than 40 and a density less than or equal to 3.2 g / cm ³ .

It has been found that photochromic glasses, which contain precipitates as carriers of the phototropy, which consist of silver, halogens and other components can be produced with a refractive index greater than or equal to 1.59, an Abbe number greater than or equal to 40 and a density less than or equal to 3.2 g / cm-, when choosing a glass composition, expressed in percent by weight on an oxide basis, the following components contains:

SiO ₂
B ₂ O ₃
P ₂ O ₅

32-47
14.5-27
0-11

where: 2 SiO ₂₁ B ₂ O ₃ + P ₂ O ₅ between 58.0 and 71.0

Al ₂ O ₃

ZrO ₂

La ₂ O ₃

Nb ₂ O ₅

WHERE ₃

0-0.4
1.5-10
0-23
0-2
0-1

where: 2 Al ₂ O ₃ , ZrO ₂ , La ₂ O ₃ , Nb ₂ O ₅ + WO ₃ between 2.0 and 25.0

MgO
CaO
SrO

0-1
0-6
0-24

where: 2 alkaline earth oxides between 0 and 24.0

PbO
TiO ₂

0.5-12
0.5-8

and where: 2 La ₂ O ₃ , SrO, PbO, TiO ₂ , Nb ₂ O ₅ , ZrO ₂ , WO ₃ between 12 and 34

Li ₂ O 0.5- 6 Na ₂ O 0-4 K ₂ O 6-12

where: 2 alkali oxides between 6.5 and 15

the glass having at least 0.1% by weight of Ag ₂ O, at least 0.004% by weight of copper oxide, at least 0.1% by weight of bromine and at least 0.1% by weight of chlorine as the carrier of phototropy

A content of P ₂ O ₅ in a concentration between 0.01 and 11% by weight is favorable for the chemical resistance of the photochromic glass.

Instead of or in addition to PbO, ZnO can also be used, and instead of or in addition to TiO _{2 , SnO 2} can also be used and instead of

ίο or in addition to La ₂ O ₃ or Nb ₂ O _{5 , Ta 2} O ₅ can also be used in approximately the same molar amount.

Instead of La ₂ O ₃ , other rare earth oxides or mixtures of La ₂ O ₃ and other rare earth oxides can also be used.

To produce a brown color when exposed, the glass can be doped with noble metals.

To produce color tones in the unexposed state, the glass can be filled with a total of 1% by weight of subgroup metal oxides and / or a total of 5% by weight (additional) coloring rare earth metal oxides offset.

If the silver halide-containing, photochromic glasses according to the invention are irradiated by actinic When exposed to light, photolysis is effective in these precipitates containing silver halide. That included Developed silver grows into silver colloids and generates absorption in the visible spectral range. If the photochromic glass is no longer stimulated by appropriate radiation, the system returns to its Initial state back.

For the production of the photochromic glasses according to the invention and the adjustment of their photochromic properties, not only the introduction of silver and halogens and copper oxide into the glass is necessary, but preferably also a tempering of the glasses. (The heating of the glasses to 500 to 720 ^° C. for a period of 26 hours to 10 minutes is defined as tempering.) The quality of the product is influenced by the selected concentrations.

If the concentration of silver is too low with a sufficient amount of halogens, the glass will tend during tempering to cloudiness. As the silver content increases, this cloudiness goes down, and then it becomes one increasing blackening observed in the excited state. However, if the silver concentration is too high, even the untempered glass tends to become cloudy. There is also an influence of the silver concentration determine the kinetics of the photochromic process. If the silver content is too low, the kinetics are poor; with With increasing concentration of the silver, the kinetics improve until they are again at too high a content worsened. The optimal silver concentration for each individual glass composition can only be determined through serial tests to be determined, but it should not fall below 0.1% by weight in the analysis.

The commonly used halogens are bromine and chlorine, but if only one is chosen, then the halogens will be used of the two halogens mentioned photochromic properties found in the glasses according to the invention.

From a technical point of view, setting the appropriate halogen concentration is somewhat complicated, since the vapor pressures of these components are very high at the melting temperature.
The effect of the halogen concentration on the photochromic properties is similar to that of silver. Insufficient amounts of chlorine and bromine cause the tempered glass to become cloudy; the phototropy is only very weak. With increasing halogen concentration

the photochromic properties were strengthened; the kinetics improves and the blackening in the excited state decreases. If the halogen level is too high, Even the untempered glass shows cloudiness.

For each selected composition of the glasses according to the invention, the suitable halogen concentration and the ratio of the halogens to one another must be determined by series of tests, but the concentrations of bromine and chlorine should not fall below ^{0.1% by weight J / b.}

When CuO is introduced into a copper-free phototropic glass, it improves as the copper oxide content increases the kinetics of the phototropic process; in addition, the glass is less able to darken and to notice a higher temperature dependence.

The setting of the copper concentration in the photochromic glass is decisive for the kinetics and the achievable blackening depth; it also influences the temperature dependence of the photochromic Process.

If a CuO content of less than 0.004% by weight is chosen, the kinetics appear to be too being bad for ophthalmic applications of the glasses.

Table 1 shows examples of glasses according to the invention in% by weight; All glasses were synthesized with 0.27% by weight of Ag ₂ O, 0.64% by weight of Cl; 1.21% by weight Br and 0.006% by weight CuO were added.

The data in Table 1 mean: rid is the refractive index, D is the density in g · cm- ³ , the Abbe number is marked as Vd , RHWZ is the regeneration half-life in minutes after a standard exposure of 15 minutes with 80,0001 χ xenon light, at which the saturation transmission ST in% (measured at 545 nm) was achieved. R 30 is the transmission value in% that the glass reaches after 30 minutes of regeneration. All phototropy data are determined on 2 mm thick samples at 20 ^° C.

The lenses according to the invention have a refractive index greater than or equal to 1.59, an Abbe number greater than or equal to 40 and a density less than or equal to 3.2 g / cm ³ , good chemical resistance and can be ground and polished like optical lenses without difficulty.

All examples according to the invention can be used with silver, halogen and copper concentrations other than those indicated melt in such a way that the photochromic properties are varied.

All glasses according to the invention can be used for constant coloring with coloring metal compounds, such as NiO or CoO etc. are added.

Embodiment

The following example explains the production of a glass according to the invention.

number
1 2

SiO ₂ 35.00 - 2.00 - 35.00 34.00 44.10 B2O3 26.00 1.50 10.00 26.00 25.00 20.00 P ₂ O ₅ 1.55 0.50 100.00 0.50 0.25 0.25 Al ₂ O ₃ 1.00 1,593 - 0.10 0.10 ZrO ₂ 1.00 58 2.00 4.00 5.50 La ₂ O ₃ 5.50 2.85 1.50 1.00 5.50 Nb ₂ O ₅ 2.50 32 0.50 0.20 0.20 WHERE ₃ 8.95 2.4 1.00 0.50 0.50 MgO 2.50 75 - 0.20 0.20 CaO 2.00 4.50 6.00 0.50 SrO 2.50 1.00 8.00 PbO 10.50 10.55 1.55 TiO ₂ 3.50 3.00 5.70 Li ₂ O 2.00 3.00 2.20 Na ₂ O - 0.20 2.20 K ₂ O 10.00 10.00 9.00 99.50 99.60 100.20 nd 1.6040 1,609 1,609 vd 62 60 48 D (gcm-3) 2.87 2.90 2.74 ST ( ⁰ Zo) 27 36 30th RHWZ (mm) 3.2 3.0 3.5 RiO (Oh) 78 78 75

Batch recipe 662.4 g ground quartz sand 531.5 g Boric acid 3.8 g Phosphorus pentoxide 1.9 g Aluminum monohydrate 82.8 g Zirconium oxide 3.0 g Niobium pentoxide 7.5 g Tungsten oxide 7.6 g Magnesium carbonate 201.6 g Potassium carbonate 22.3 g Strontium carbonate 53.6 g Red lead 85.9 g Titanium oxide 82.5 g Lithium carbonate 56.7 g sodium 135.0 g Potassium carbonate 33.3 g Potassium bromide 47.3 g Potassium chloride 8.8 g Silver nitrate 0.3 g Copper oxide

40 The ingredients of the batch are weighed in and mixed. The mixture is placed in a 1-1 platinum crucible at 1365 ° C and melted. The glass melt is then refined at 1410 ° C., then cooled to 1345 ° C. and homogenized by stirring for 18 minutes. The melt is then rolled out into 4 mm thick, 70 mm wide glass bars.

The heat treatment is carried out at 630 ^° C. for 1 h in an air circulation oven, followed by cooling to room temperature at 40 K / min.

On this glass were

a refractive index /? </ of 1.605,
a dispersion Vd of 50.0 and

a density £> of 2.79 g cm ^-3

measured.

The measurement of the phototropic characteristics resulted in a 2 mm thick glass ^{at 20 ° C.}

Saturation transmission of 29%,

a regeneration half-life of 3.6 min and

a transmission of 78% after 30 minutes of regeneration.

Claims (1)

Patent claims: 1. Phototropic borosilicate glass, which has precipitates containing silver, halogens and copper oxide as a carrier of the phototropy and which has a refractive index> 1.59, an Abbe number> 40 and a density <3.2g - cm- ³ , characterized in that it, expressed in percent by weight on an oxide basis contains: SiO ₂
B ₂ O ₃
P ₂ O ₅ 32-47
14.5-27
0-11 where: 2 SiO ₂₁ B ₂ O ₃ + P ₂ O ₅ between 58.0 and 71.0 Al ₂ O ₃ ZrO ₂ La ₂ O ₃ Nb ₂ O ₅ WHERE ₃ 0-0.4
1.5-10
0-23
0-2
0-1 where: 2 Al ₂ O ₃ , ZrO ₂ , La ₂ O ₃ , Nb ₂ O ₅ + WO ₃ between 2.0 and 25.0 MgO
CaO
SrO 0-1
0-6
0-24 where: 2 alkaline earth oxides between 0 and 24.0 PbO
TiO ₂ 0.5-12
0.5-8 and where: 2 La ₂ O ₃ , SrO, PbO, TiO ₂ , Nb ₂ O ₅ , ZrO ₂ , WO ₃ between 12 and 34 Li ₂ O 0.5- 6 Na ₂ O 0-4 K ₂ O 6-12 where: alkali oxides between 6.5 and 15 and as a carrier the phototropy in addition to the basic glass composition